Studies on the determination of mercury by on-line solvent extraction and non-aqueous media hydride generation non-dispersive atomic fluorescence spectrometry

A new method for on-line solvent extraction covalent hydride generation in a non-aqueous extraction phase is proposed. Both liquid-liquid extraction and gas-liquid separation steps are accomplished in an online mode and with AFS as detector. Hydride generation is carried out in an aliquot of metal-complex extraction solution by sodium tetrahydroborate in N,N-dimethylformamide solution and anhydrous acetic acid. An improved U-type gas-liquid separator was used. The working conditions and manifolds scheme of flow injection were optimized. The detection limit attained for mercury was 20 ng L-1. The precision of the determination at a concentration level of around 20 times the detection limit was 5.6%. The proposed method gives improved sensitivity and eliminates interference. The method has been applied to the determination of mercury in certified reference materials with good accuracy and precision.